A variety of domino games are presently known, most of which typically use a number of flat, oblong-shaped game pieces. Each game piece has a face that is divided by a transverse line to form two generally square sections. Each section is inscribed with indicia that represents a particular value. Typically, such indicia takes the form of a number of depressions, commonly called pips, that appear in each section to a numeral that can range from naught to any number, depending upon the size of the domino set.
Most known conventional domino games are played by forming a line of domino game pieces of any type of flat playing surface (e.g., a table) as players make their plays, generally, but not always, by matching the numerals on the faces of the game pieces. That is, each domino game piece is laid face up on the table for play so that the piece played with match and adjoin an open end of the already played game pieces, a five being played to a five, a three being played to a three, and so on.
Scoring is accomplished by totaling, in one fashion or another, the depressions (or numerals represented thereby) that appear at the ends of the line of play as the game progresses. For example, the most common domino game, Muggins, is played by laying the tiles so as to make the number of depressions at the ends of the line of play add up to multiples of five. Points are awarded for each five depressions made.
Many other games have variations of play, but so far as is known, all use generally the same method of scoring, i.e., the addition of depressions in one manner or another. An excellent discussion of the various domino games that may be played can be found in "The Domino Book" by Frederick Berndt, published by Bantam Books, Inc. of New York, New York.
Typically, domino sets are referred to as double-N sets, with N representing the highest numeral appearing on the face. A typical set of domino game pieces consists of 1/2(N+1) (N+2) individual game pieces. Game pieces having the same numeral appearing on one section of their faces form a "suit". The game pieces of each suit have a numeral (usually represented by the depressions discussed above) appearing on the remaining section of their faces running consecutively from the numeral of the suit down through blank. Thus, for example, a double-six set would consist of 1/2(6+1)(6+2) or 28 game pieces having the following values:
(1) Double-six, six-five, six-four, six-three, six-two, six-one, six-blank; PA1 (2) Double-five, five-four, five-three, five-two, five-one, five-blank; PA1 (3) Double-four, four-three, four-two, four-one, four-blank; PA1 (4) Double-three, three-two, three-one, three-blank; PA1 (5) Double-two, two-one, two-blank; PA1 (6) Double-one, one-blank; and PA1 (7) Double-blank.
However, so far as is known, no domino game combines adding and subtracting the numerals or depressions that appear at the ends of the line of play in a single game.